Setarious aristate: the dipterous antenna when the arista is simple.
Setiform: in the form of a bristle or seta: when a slender short bristle arises from a thicker basal joint.
Setigenous: the hypodermal cells that give rise to setae.
Setigerous: bearing setae or bristles; e.g. punctures.
Setireme: the hairy, oar-like legs of aquatic insects.
Setose -ous: bristly or set with bristles.
Setula: a small stiff bristle or seta: in Diptera, the small thorn at the end of the sub-costa.
Setulose: clothed with fine seta or setulae.
Sex: as a number, six: the physical difference between male and female: usually indicated by the sign of Mars (?) for male, and Venus (?) for female; workers or undeveloped females have the sign of Venus without the cross line, or a combination of the two others.
Sexuparae: that generation of plant lice which produces the true sexes.
Shade: a cloudy, ill-defined streak or band.
Shagreened: a surface roughened with minute tooth-like projections.
Sharp: with a pointed tip or thin edge; opposed to blunt.
Sheath of penis: in Odonata, a median, hood-like piece between the hamules, under which the penis is folded when not in use.
Short sector: in Odonata, = media 4 (Comst.).
Shoulder: loosely applied to an obtuse angulation; more generally to the humeral angle of fore wings or elytra: the anterior angles of thorax in Lepidoptera; the angles of prothorax in Heteroptera: the lateral angles of metazona of pronotum in Orthoptera.
Side piece: in genitalia of male Culicids the main lateral part of the clasping organ or basal segment of clasp.
Sides of thorax: in Odonata, includes the pleura of meso- and meta- thorax, less the meso-episterna.
Sigmoid: shaped like the Greek letter sigma, or English S.
Signate -us: = with marks or spots; see notate.
Signature: a colored blotch of any size or shape.
Silk: the hardened salivary secretion of certain larvae, mainly of Lepidoptera. similar material is produced by anal glands of some larva in Neuroptera.
Silk-glands: a pair of modified salivary glands in certain larva, mostly of Lepidoptera that secrete a viscid fluid which, on contact with the air, hardens into a silken fibre.
Silvicolous: living in moist, shady woods.
Simple, Simplex: without process, armature, or appendage of any kind.